The idea here is to prefer simple solutions, hoping that the simple solution will pay off in the long term by reducing current and future design and maintenance cost.
Managing Simplicity posits that this will be true enough of the time to make it a default choice. Of course you have to look at opportunity cost, and weights of risks, rewards, and efforts.

Here are the areas where Managing Simplicity spells out steps that are proven to save effort in the long run.

The Refactoring Rule of Three.

The first time, just write the code to get it to work.
The second usage, copy the code, make it work for the new instance.
The third usage, look for commonality, and do a simple refactoring.
So any time you have four blocks of code that smell of Cut-and-Paste, look to refactor the code in the simplest way to eliminate redundancy.

When you get to three redundancies at the next level, then consider fancier refactorings. That is, the following code is redundant, but OK, because it is only done twice:

Friday, June 17, 2011

This is a bit of a ramble, but contains links to get started using GWT, and some notes on how to use Eclipse and IntelliJ IDEA for GWT development.

For http://anarchia.us I plan to deploy using http://dynamide.com as the templating engine for browsing all the content. But the Author interface (that is, the interface that authors must use to upload content, manage identity, choose frame layouts, make story trails, and assign copyrights), is a real app. It has business rules, editing of one-to-many relations, and many of the things that make application development and deployment difficult via a web interface. I had planned to deploy this app as a pure java client using http://tagland.org , but the tagland client still needs a heap of work. I could use dynamide for this app, but there is a lot of back and forth to the server, and dynamide, being form-based, would make this a bit too web-1.0.

Enter Google Web Toolkit (GWT). I decided on using GWT for the Author interface because it promises cross-browser functionality, and AJAX communication to the server. Downsides: it is complicated; it has a slow load time; it has a number of moving parts that are inaccessible. I decided that the slow load time was acceptable for the Author interface since it is basically an admin application--designed to be used by a limited number of authors who are motivated to use the system, compared with the browsing interface which will be used by anyone on the web. After some initial testing, I also found that complications seemed to be in the build and deploy process, and not in the browser environment, so could be managed like any other software complexity. I also found during prototyping that all of the abstractions I really wanted were supported. GWT supports serializing real java objects across the wire with its own RPC mechanism, and supports construction of the UI by composition of components. Another plus of GWT, for a Java programmer, is that all the code and logic are in Java. So you get compile-time checking of everything, strong typing, exceptions, etc. This goes a long way towards managing simplicity. On balance, it seemed that GWT managing of complexity was the way to go rather than managing that complexity directly with something like jQuery.

On to the things I learned while prototyping GWT.

First, you can see the actual code I used here: http://tagland.sourceforge.net . There are some dependencies, so you'll probably need to check out the whole project. Look in module anarchiaAuthor. This project compiles in IntelliJ IDEA 10.5.

GWT is supported in Eclipse and IntelliJ IDEA. Eclipse supports a UI designer tool which is very cool. They both generate sample applications for you, which is the only way to get started. The flavor of AsyncCallback that the use is a bit different. Eclipse generates inline anonymous classes; IDEA generates named, inner classes. I'm a fan of IDEA, so once I established that they both worked, I moved on to developing all my code in IDEA. IDEA has slightly better inspections and jumps between Java, XML, and HTML files in the project a bit better. Eclipse generates the deployment files correctly, which is to say, all the files with MD5 sums in their names, which are browser-specific files for deploying to all supported browsers. In IDEA 10.5 (they say they'll fix this in 10.5.1) you need to add two jars to your classpath to get this to work. In Project Structure > Libraries > gwt-user > Classes, you need to click "Attach Classes", then point to your local GWT installation dir, where you must find validation-api-1.0.0.GA.jar and validation-api-1.0.0.GA-source.jar. Accepting these files should add the jar files to the classes node (not to the sources node).

To get started in IDEA with GWT, I followed this screen-cast *very* closely, using the pause button frequently. http://www.jetbrains.com/idea/training/demos/GWT_Basics/GWT_Basics.html . Basically, you install the GWT plugin, then create a new Java module, and then specify that it uses Google Web Toolkit, making sure to check the checkboxes that ask if you want it to create a source directory and if you want it to create a sample application.

I found this article to be thorough and well written:http://www.vogella.de/articles/GWT/article.html
It also got me past one of the big humps, which was how to let GWT know about dependent modules so I could use GWT as a layer, rather than an all-in-one solution. This is important if you want to keep from copying code or source jars around, and if you want to keep from getting everything wrapped up in GWT land so that you can't pursue other implementation strategies. Specifically, I found this section very helpful: http://www.vogella.de/articles/GWT/article.html#modules

There are two things going on when you import modules. First, you have to get your IDE to know about the modules. Second, you have to get GWT to find the source code, so that it can translate it into javascript, which is the magic that makes GWT work.

The above article shows how to do this in Eclipse. In IDEA, you should also follow the article on how to do GWT module imports, then you must create an IDEA module in your main project, call it a Java module, and add dependencies on lib directories. In tagland, tagland is the main project, anarchiaAuthor is the GWT module (a Java module with a Google Web Toolkit feature selected on the second or third page of the New Module wizard), and anarchia-obj is a Java module that contains just the serializable, GWT-friendly POJOs. (POJOs are GWT-friendly if they don't import things that can't be serialized and sent to the client. The list is here: http://code.google.com/intl/pl-PL/webtoolkit/doc/2.2/RefJreEmulation.html . You'll find that things like java.net.URL are not included.) anarchiaAuthor, being a GWT module, has a WEB-INF/lib directory, and that must be added in the project as a lib directory, and that lib must be added as a dependency in the module settings. anarchia-obj, being a POJO module, must be added as a dependency in the module settings for anarchiaAuthor.

"No source code is available for type java.net.MalformedURLException; did you forget to inherit a required module?"

You'll get these kinds of errors if you don't have the source code for the classes you want to serialize included properly in the IDE and in the imports statement for GWT. For IDEA, you sometimes need to restart IDEA after fiddling with the GWT imports statements.

You will get all kinds of strange errors if you try to send anything across the wire that cannot be serialized and emulated by GWT. In IDEA, be sure to look on the Modules tab of the Run window for the log.

You will also get errors if you include jars in your lib directory that have older sax parsers. The solution is to clean out your lib directory, and add things slowly until the error appears. These can look like this:

[WARN] Unable to process 'file:/Users/laramie/Library/Caches/IntelliJIdea10/gwt/tagland.90e8b9ba/anarchiaAuthor.4b3edb74/run/www/WEB-INF/web.xml' for servlet validation javax.xml.parsers.ParserConfigurationException: AElfred parser is namespace-aware at com.icl.saxon.aelfred.SAXParserFactoryImpl.newSAXParser(SAXParserFactoryImpl.java:37) at com.google.gwt.dev.ServletValidator.create(ServletValidator.java:191) at com.google.gwt.dev.ServletValidator.create(ServletValidator.java:172) at com.google.gwt.dev.DevMode.doStartup(DevMode.java:426)"

This give you a clue that can help when figuring this stuff out. Note the location of the WEB-INF directory. This is the deployed location, so go in there, and look in WEB-INF/lib, and see what has been deployed. In my case it was extra sax parsers that were incompatible with the one GWT wanted to use.

Monday, April 11, 2011

Menus are installed in a space. A menu is just a text file or collection of files, capable of storing hierarchy structure, and all data and algorithms to invoke an action based on a command chosen in a context.

Multiple menus can live in one space. Menus can call each other in the same space with a different security context than calling menus in other spaces.

The context is in the space. The context may be a sandbox with a namespace of variables and commands. But that context is in the space.

The space is just data; can also be represented as a directory of files.

Ultimately a space lives in a JVM, there is an uber-sandbox of Java class files to provide an API to the space, to the commands in the space.

A space is data. These data can be closed and exported to another machine.

So very quickly we have the problem of synchronizing spaces.

Some spaces will be very data-centric, will be about storing data, or metadata. Others will be more atuned to a user's desires. Data-centric spaces will have p2p, federated backup and sync, or publish-subscribe strategies for synchronization. The personalization spaces will have to follow the user more closely, e.g. actually stored on user's person, e.g. cell phone sdcard. Or perhaps biometric or passphrase based user identification for opening a write session to a hosted space. Or maybe, spaces allow mulitple users to log in and change a space. So you log into a space, and are perhaps simultaneously logged in to other spaces you need. Your master local session keeps track of these spaces, and marshalls data between spaces based on permissions.

All messages to menus, API objects, etc., use an XML payload input and output objects. The function name, plus the type (schema) of objects they require and return defines the API.

Thursday, March 24, 2011

Which4jI wrote one of these for Vestek, but this might be useful, seeing how it is open source. Anyway, it is nice to have a utility which tells you in which location on your classpath a java Class is actually found. http://java.net/projects/which4j

TrueZipThis is the bomb. Archives as federated filesystems. (Zip, tar, jar, etc.) This will be needed by diorama for dealing with personal spaces. My concept of Spaces is to mount a jar file, then write to it, then unmount and share it, with whatever level of encryption. Your project's tips-n-tricks, help files, etc., would be in a public space. Your contacts would be in a private, encrypted space. Then those spaces get sync'd through your server/account, and shared as appropriate. This library, TrueZip, looks perfect for the implementation because it handles multithreaded access to the archive at runtime. http://java.net/projects/truezip

Monday, February 28, 2011

I just tried to install Java 1.6 (i.e. Java 6) on my 4 processor PowerMac, after having followed the instructions and paid $150 for a new MacOS Leopard 1.5.6 Operating System, and applied all the updates up to 1.5.8 in order, including all the Java updates from Apple. "Oooooooooh Sooorry, you can't run Java 6 because *you don't have an Intel processor!*" What!?

Without Java, my Mac is good for running ProTools, which I do. But without Java, I can not do the work that I get paid to do, which is to be a Java programmer. So this machine is useless if I want to use it for work. But also, any Java app written since 2008 has the right to rely on Java 6. So a whole raft of applications can't be deployed on a PowerPC-based Mac.

Now hold on, you say. Your PowerMac G5 is 6 years old! (Never mind that Java 6 was released the same year my G5 was.) But, I say, you haven't looked inside this machine. It easily cost twice what commodity hardware would have cost me at the time I bought it. It is made from machined aluminum. It has a liquid cooled core with a radiator. It has machined, well-designed, beautiful, expensive parts. This machine was built to last twenty years if you keep the dust out of it. And Apple built a reputation on backwards compatibility and support. Well that's all gone now, it seems. They are playing the same game Microsoft is: every two to three years you should buy a new Mac, preferably in the $3,000 - $4,000 range. Because it's better hardware. It will outlast your crappy Dell which dies after two years because of crappy, proprietary power sub-sytems. But what does it matter if the hardware lasts, if the OS doesn't get upgraded?

Also, as I see it, I can not now use my PowerMac if I want to use the best programming language in the world, that is widely accepted, and may be one of the languages that we could have standardized on. Except everyone wants to kill Java. Microsoft wanted to kill it so much that they intentionally broke their own implementation, and wrote a competing look-alike language, with the help of a hired gun: Anders Hejlsberg, the designer of Delphi from Borland, who contributed in a big way to the Java component model. Oracle wants to kill Java, too. They wanted to kill it so badly, they bought it along with Sun Microsystem, and made it even more proprietary than Sun had. Oracle allows us a quasi-open-source solution called OpenJDK which will build on Linux, but is a time-lag from the main development line. This appeases folks, and is mosly available and free, but it means they retain control. What the world needs is an open source language as robust, secure, mature, fast, and good as Java, that is not owned by any for-profit-corporate entity.

Mac wanted to kill Java so badly, they insisted that no one else could build Java for the Mac. Then they don't release security updates when the fixes are available. Then they decide to not support Java 6 on non-Intel macs. The tech support lady, when I asked her if I now had a $4000 brick, said that if I wanted to run Java 6 that I'd need to upgrade my entire system to Intel. Since when is buying a new machine called "upgrading?"

Then there's Apple's refusal to distribute Java on the iPhone. Tiny devices that are intermittently connected to network are what Java was designed for. Most phones have Java. The Android phones are making a smashing success using Java. So why doesn't Apple want to support Java on their phone?

So why do I claim that everyone wants to kill Java? I don't have a smoking gun, just this: if you have Java, it's one step closer to not needing a branded operating system. Java is a system you can run on a computer that will run many kinds of applications, and replaces many core operating system features. And does it in a particularly device-independent, OS-independent, network-aware way.

But you can't make money selling operating systems that don't have some sex appeal, and you can't have sex appeal without branding. So coming up with 5 new apps that flip pages in 3D is more important than providing security updates and version updates to core frameworks. Especially if those frameworks don't have happy little nibbled apple cores floating in a rotating 3D purple-starred galaxy.

So the Hell with Apple, and Microsoft and Larry Ellison. Software moves too fast for maturity. That's not Larry's fault. It's just that Larry, Bill, and Steve know this and have figured out how to make money on this mayhem.